From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hugh Dickins Subject: Re: v4.2-rc dcache regression, probably 75a6f82a0d10 Date: Fri, 31 Jul 2015 21:20:26 -0700 (PDT) Message-ID: References: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Hugh Dickins , "J. Bruce Fields" , Dominique Martinet , Dominique Martinet , David Howells , Al Viro , Linux Kernel Mailing List , linux-fsdevel To: Linus Torvalds Return-path: Received: from mail-pa0-f46.google.com ([209.85.220.46]:36728 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750815AbbHAEVX (ORCPT ); Sat, 1 Aug 2015 00:21:23 -0400 Received: by pachj5 with SMTP id hj5so50820970pac.3 for ; Fri, 31 Jul 2015 21:21:23 -0700 (PDT) In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Fri, 31 Jul 2015, Hugh Dickins wrote: > On Fri, 31 Jul 2015, Linus Torvalds wrote: > > > > So leave it running a while longer, but maybe it's 4bf46a272647 like > > Dominique suspects. Although I don't see how that could trigger > > anything either.. > > I restarted with a slightly different version of the load this > morning, which has sometimes shown the issue more easily - I thought > it better to restart with a variant than persist with a run that > might have settled into a protected pattern. We'll see what that > shows later on. It showed nothing useful to this discussion: after an hour and a half it had hung on some almost-certainly-unrelated issue that I've never seen before - looked as if a jbd2 transaction never completed, some tasks waiting for that, some waiting for f_pos_lock held by those (which I hit when I tried to tail the output log). Worry about that another time, if it ever shows up again. I think I'll try reinstating Al's commit, and hacking out that change of David's in dentry_iput() that worried me (though the "especially problematic" remark in his change description suggests that it is an intentional and necessary change to suit unionmount). See how that goes. Hugh